'wide-fitting' is a compound of 'wide' and 'fitting'. 'wide' originates from Old English, specifically the word 'wīd', where 'wīd' meant 'broad'. 'fitting' comes from the verb 'fit', which originates from Old English, specifically the word 'fittian' (verb) meaning 'to be suitable' or 'to fit'.

'wide' changed from Old English 'wīd' and continued into Middle and Modern English as 'wide'. 'fit' evolved from Old English 'fittian' to Middle English forms like 'fitten'/'fit' and then to the modern English verb 'fit'; the compound 'wide-fitting' formed in Modern English by combining 'wide' + present participle 'fitting' to describe garments.

Initially the component words meant 'broad' (for 'wide') and 'to be suitable/fit' (for 'fit'); over time the compound came to be used specifically to describe clothing or items that 'have a broad or roomy fit' and is used adjectivally.